Modeling of Losses Due to Inter-Laminar Short-Circuit Currents in Lamination Stacks

Open access


The cores of electrical machines are generally punched and laminated to reduce the eddy current losses. These manufacturing processes such as punching and cutting deform the electrical sheets and deteriorate its magnetic properties. Burrs are formed due to plastic deformation of electrical sheets. Burr formed due to punching on the edges of laminated sheets impairs the insulation of adjacent sheet and make random galvanic contacts during the pressing of stacked sheets. The effect of circulating current occurs if the burrs occur on the opposite edges of the stacks of laminated sheets and incase of bolted or wielded sheets, induced current return through it. This induced current causes the additional losses in electrical machine. The existence of surface current on the boundary between two insulated regions causes discontinuity of tangential component of magnetic field. Hence, based on this principle, the boundary layer model was developed to study the additional losses due to galvanic contacts formed by burred edges. The boundary layer model was then coupled with 2-D finite element vector potential formulation and compared with fine mesh layer model. Fine mesh layer model consists of finely space discretized 950028 second order triangular elements. The losses were computed from two models and were obtained similar at 50 Hz. The developed boundary layer model can be further used in electrical machines to study additional losses due to galvanic contacts at the edges of stator cores.

[1] D. M. Lindenmo and A. Coombs, ”Advantages, properties and types of coatings on non-oriented electrical steels,” Journal of Magnetism andMagnetic Materials, Vol. 215-216, pp. 79-82, 2000.

[2] A. Kedous-Lebouc, B. Cornut, J. Perrier, P. Manfe and T. Chevalier, ”Punching influence on magnetic properties of the stator teeth of an induction motor,” Journal of Magnetism and Magnetic Materials, Vol. 254-255, pp. 124-126, 2003.

[3] A. Boglietti, A. Cavagnino, L. Ferraris and M. Lazzari, ”The annealing influence onto the magnetic and energetic properties in soft magnetic material after punching process,” IEEE Electric Machines and DrivesConference, 2003.

[4] K. Schmidt, ”Influence of punching on the magentic properties of electric steel with 1% silicon,” Journal of Magnetism and magneticmaterials, vol. 2, no 1-3, pp. 136-150, December 1975.

[5] A. Moses, N. Derebasi, G. Loisos and A. Schoppa, ”Aspects of the cut edge effect stress on the power loss and flux density distribution in electrical steel sheets,” Journal of Magnetism and Magnetic Materials, Vol.215-216, pp. 690-692, 2000.

[6] M. Emura, F. Landgraf, W. Ross and J. Barreta, ”The influence of cutting technique on the magnetic properties of steel,” Journal ofMagnetism and Magnetic materials, Vol.254-255, pp. 358-360, 2003.

[7] A. Moses and M. Aimoniotis, ”Effects of Artifical Edge burrs on the properties of a Model transformer core,” Physica Scripta, vol. 39, pp. 391-393, 1989.

[8] P. Beckley, Electrical steels for rotating machines, The Institution of Engineering and Technology, London, 2002.

[9] Technical drawings-Edges of undefined shape Vocabulary andindications, International Standard ISO 13715:2000.

[10] S. L. Ko and A. D. Dornfeld, ”A study on burr formation mechansim,” Transaction of the ASME Journal of Engineering Material andTechnology, vol. 113, no 1, pp. 75-87, 1991.

[11] L. K. Gillespie and P. T. Blotter, ”The formation and properties of machining burrs,” Journal of Engineering for Industry, vol. 98, no 1, pp. 66-74, 1976.

[12] P. Baudouin, M. Wulf, L. Kestens and Y. Houbaert, ”The effect of the guillotine clearance on the magnetic properties of electrical steels,” Journal of Magnetism and Magnetic Materials, vol. 256, pp. 32-40, 2003.

[13] J. Aurich, D. Dornfeld, P. Arrazola, V. Franke, L. Leitz and S. Min, ”Burrs-analysis, control and removal,” CIRP Annuals-Manufacturingtechnology, vol. 58, no 2, pp. 519-542, 2009.

[14] A. Boglietti, A. Cavagnino, M. Lazzari and M. Pastorelli, ”Effect of punch process on the magnetic and energetic properties of soft magnetic material,” Electric machines and drives conference,IEMDC 2001, pp. 396-399, 2001.

[15] M. W. Arshad, T. Ryckebush, F. Magnussen, H. Lendenmann, J. Soulard, B. Eriksson and B. Malmros, ”Incorporating lamination processing and component manufacturing in electrical machine tools,” Industry Applications Conference, 2007. 42nd IAS Annual meeting, 2007.

[16] F. Ossart, E. Hug, O. Hubert, C. Buvat and R. Billardon, ”Effect of punching on electrical steels: Experimental and numerical,” IEEETransactions on Magnetics, vol. 36, no 5, pp. 3137-3140, 2000.

[17] R. Mazurek, H. Hamzehbahmani, A. J. Moses, P. I. Anderson, F. J. Anayi and T. Belgrand, ”Effect of Artificial Burrs on Local Power Loss in a Three-Phase Transformer Core,” IEEE Transactions on Magnetics, vol. 48, pp. 1653 -1656, 2012.

[18] R. Mazurek, P. Marketos, A. Moses and N. J. Vincent, ”Effect of artifical burrs on the total power loss of a three phase transformer core,” IEEEtransaction on magnetics, vol. 46, pp. 638-641, 2010.

[19] R. Jean-Yves, V. Emmanuel, H. Thomas, B. Abdelkader and D. Jean- Pierre, ”Electromagnetic modelling of short circuited coreplates”.

[20] S. B. Lee, G. Kliman, M. Shah, W. Mall, N. Nair and R. Lusted, ”Advanced technique for detecting interlaminar stator core faults in large electric machines,” IEEE transaction on Industry application, vol. 41, pp. 1185-1193, 2005.

[21] H. Igarashi, A. Kost and T. Honma, ”Impedance boundary condition for vector potentials on thin layers and its application to integral equations,” The European Physical Journal Applied Physics, vol. 1, no 1, pp. 103-109, 1998.

[22] C. Brebbia, Topics in Boundary Element research, Springer Verlag Berlin, 1989.

[23] L. Krahenbuhl and D. Muller, ”Thin layers in electrical engineering example of shell models in analysing eddy currents by boundary and finite element methods,” IEEE transaction on Magnetics, vol. 29, pp. 1450-1455, 1993.

[24] C. Geuzaine, P. Dular and W. Legros, ”Dual formulations for the modeling of thin electromagnetic shells using edfe elements,” IEEEtransactions on Magnetics, vol. 36, pp. 799-803, 2000.

[25] J. Gyselinck, R. Sabariego, P. Dular and C. Geuzaine, ”Time domain finite element modeling of thin electromagnetic shells,” IEEEtransaction on Magnetics, vol. 44, pp. 742-745, 2008.

[26] R. Sabariego, C. Geuzaine, P. Dular and J. Gyselinck, ”Non-linear time domain finite element modeling of thin electromagnetic shells,” IEEEtransaction on magnetics, vol. 45, pp. 976-979, 2009.

[27] C. A. Schulz, S. Duchesne, D. Roger and J. N. Vincent, ”Capacitive short circuit detection in transformer core laminations,” Journal ofMagnetism and Magnetic Materials, vol. 320, no 20, pp. 911-914, 2008.

[28] G. Iaccarino, Uncertainty quantification in computation science, Department of Mechanical Engineering Stanford University, 2011.

[29] J. Luomi, Finite element methods for electrical machines, Goteborg: Chalmers University of Technology, Department of Electrical Machine and Power electronics, 1993.

[30] J. Van der veen, L. Offringa and A. Vandenput, ”Minimising rotor losses in high speed high power permanent magnet synchronous generators with rectifier load,” Electric Power Applications, IEEE Proceedings, vol. 144, pp. 331-337, 1997.

[31] K. Beddek, Y. L. Menach, S. Clenet and O. Moreau, ”3-D Stochastic spectral finite element method in static electromagnetism using vector potential formulation,” IEEE transaction om magnetics, vol. 47, no 5, pp. 1250-1252, 2011.

[32] E. D. Taylor, ”The measurement of interlaminar resistance of varnish insulated silicon steel sheet for large electrical machines,” Proceedingsof IEE-part II : Power engineering, vol. 98, no 63, pp. 377-385, 1951.

Electrical, Control and Communication Engineering

The Journal of Riga Technical University

Journal Information


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 57 57 25
PDF Downloads 14 14 9